Asbestos bulk materials

This method describes the collection and analysis of asbestos bulk materials by light microscopy techniques including phase- polar illumination and central-stop dispersion microscopy. Some terms unique to asbestos anaiysis are defined beiow ... 

Asbestos fibres in air Asbestos in bulk material Azodicarbonamide in air Benzene in air... 

MDHS 77 Asbestos m bulk materials - Sampling and identification by polarized light microscopy (PLMj... 

The industrial hygienist should have a stock of accurately labelled bulk materials for reference in order to know which kinds contain asbestos and which contain fiberglass, plastic, or other nonasbestos fibers. With commercial laboratories charging between 25.00 and 75.00 for a bulk analysis for asbestos, it can be wasteful to request an analysis of a material that should have been recognized as definitely asbestos free or asbestos containing. Of course, if there is any doubt whatever, an analysis should be performed since the consequences of failure to recognize asbestos can be serious to the safety and health of exposed employees. 

Bulk Sample—A sample of suspected asbestos-containing material that is obtained from a building to be analyzed microscopically for asbestos content. Bulk sample analysis can be part of a process to assess the hazard from asbestos in a building. 

X-ray methods in analyzing air and/or bulk material samples offers the most accurate approach to estimating airborne asbestos concentrations. 

The analysis of materials that possibly contain asbestos can be carried out by various methods, however the dispersion staining microscopic technique is considered to be a quick, reliable and cost-effective method that is used by the majority of laboratories that routinely carry out this type of work. This method should be in accordance with MDHS 77 (1994), which is published by the UK Health and Safety Executive and forms part of the series of the methods for the determination of hazardous substances, titled Asbestos in Bulk Materials -sampling and identification by polarised light microscopy (PLM). 

The determination of the type(s) of asbestos present within a bulk material must be performed within a specialised safety cabinet fitted with a high efficiency HEPA filter and may be summarised as follows ... 

One of the problems associated with this analysis is that it is very difficult to accurately estimate the quantity (volume) of asbestos within a bulk material unless the asbestos fibres can be easily separated from the non-asbestos portion of the sample and their respective volumes compared. Routinely, an experienced analyst would be able to provide a visual semi-quantitative estimation, based upon their knowledge of the likely range of concentrations of asbestos within a certain type of material. This would be based upon their visual examination of the sample compared with the previous similar samples that they have analysed. However, this visual estimation can be subject to the following errors ... 

In view of the above difficulties, any estimation of the concentration of asbestos within a bulk material would therefore normally be reported as one of a series of ranges, such as trace (<2%), significant (2-50%) or substantial (>50%). 

When a bulk material is submitted for analysis, the laboratory should be able to locate and identify very small quantities of asbestos within the sample matrix. Polarised light microscopy methods should be able to detect 0.01% (lOOmg/kg) asbestos if there are no interfering factors, however the majority of building materials or products contain concentrations ranging from virtually 100% asbestos down to around 1% and therefore it should not be difficult to correctly identify whether or not asbestos is present in the majority of routine samples. 

MDHS 77 (1994) Asbestos in bulk materials, sampling and identification by polarised light microscopy (PLM), June 1994, ISBN 0-7176-0677-5. 

G) A list of the laboratories that analyzed any bulk samples of asbestos-containing material found in the school building or air samples taken to detect asbestos in the school building and a statement that each laboratory has been accredited pursuant to the accreditation program under section 2646(d) of this title. 

A) within 360 days after October 22, 1986, develop an accreditation program for laboratories which conduct qualitative and semi-quanti-tative analyses of bulk samples of asbestos-containing material, and... 

A solution or suspension must be prepared from bulk material or soil contaminated with asbestos fibers in a suitable liquid. In the case of contaminated soil a few kilograms should be taken as the minimum for analysis. Insoluble bulk samples of 2-3 g are ground to fine powder and mixed with distilled water. The way of filtration is the same as for simple water samples. 

A low-power stereo binocular microscope is used to characterize and select suspected asbestos types fibers for further examination. Evaluation of the fibrous nature, color, luster, elasticity, flexibility, and other handling properties allows the detection and subsequent identification of asbestos in bulk materials at levels down to 10 mg kg... 

Microscope slides (72 mm x 25 mm x 0.8 mm approximately) and coverslips should be of the best optical quality and of the correct thickness for obtaining quality images (usually 0.17 mm). In the case of counting a particular fiber, an assumption has to be made about the cross-sectional profile of the fiber type chrysotile is usually assumed to be cylindrical in shape, while the amphiboles are considered to have a thickness-to-width ratio of 1.6 1. Discrimination of asbestos fibers using the morphology and refractive index in such cases is aided by prior identification of the fiber types present in the bulk material using PLM or other methods. 

Is an experienced safety professional qualified to collect asbestos bulk samples to demonstrate that Presumed Asbestos-Containing Material (PACM) does not contain asbestos ... 

Instrumental Methods for Bulk Samples. With bulk fiber samples, or samples of materials containing significant amounts of asbestos fibers, a number of other instmmental analytical methods can be used for the identification of asbestos fibers. In principle, any instmmental method that enables the elemental characterization of minerals can be used to identify a particular type of asbestos fiber. Among such methods, x-ray fluorescence (xrf) and x-ray photo-electron spectroscopy (xps) offer convenient identification methods, usually from the ratio of the various metal cations to the siUcon content. The x-ray diffraction technique (xrd) also offers a powerfiil means of identifying the various types of asbestos fibers, as well as the nature of other minerals associated with the fibers (9). 

The NIST material SRM 1866a consists of a set of three common bulk mine-grade asbestos materials chrysotile, amosite and crocidolite, and one glass filter sample. SRM 1867 consists of a set of three imcommon mine-grade asbestos materials antophyllite, tremolite and actinohte. The optical properties of SRMs 1866a and 1867 have been characterized so that they may serve as primary calibration standards for the identification of asbestos types in building materials. 

SRM 1868 consists of a set of two common bulk mine-grade asbestos materials chrysotile and amosite, contained in matrices simulating building materials (calcium carbonate and glass fiber), in quantities at just below the U.S. ERA regulatory limit of I %. This material is certified by weight for the quantity of each asbestos material present. 

Fig. I.IB illustrates fibers typical of commercial asbestos, while Fig. l.ll shows Fiberglas and Fig. I.IJ silicon carbide whiskers. Some of the fibers in these examples are bent, occasionally through 180°, indicating considerable flexibility. Whiskers of other compounds can also bend but the tensile strength of these materials is their most remarkable feature. The measured values (Table 1.2) are at least ten times higher than those observed for the same compounds in bulk or in another morphology (Walker and Zoltai, 1979). The numerous investigations into the causes of this unique response have produced several hypotheses.

Gaskets - [cross-reference entry] (Vol 12) -asbestos m [ASBESTOS] (Vol 3) -magnets m [MAGNETIC MATERIALS - BULK] (Vol 15) -NBRm [ELASTOMERS, SYNTHETIC - NITRILE RUBBER] (Vol 8) -for pressure vessels [HIGH PRESSURE TECHNOLOGY] (Vol 13)... 

Percent chrysotile asbestos in bulk samples may be measured by X-ray powder diffraction (NIOSH Method 9000, 1984) sample dust grinded under liquid N2 wet sieved through 10-mm sieve sieved material treated with 2-propanol agitated in an ultrasonic bath filtered on a silver filter measured by XRD, using a Cu target X-ray tube. 

EPA. 1993a. Test method for the determination of asbestos in bulk building materials. Washington, DC U.S. Environmental Protection Agency. EPA 600/R-93/116. 

Polarized light microscopy is frequently used for determining the asbestos content of bulk samples of insulation or other building materials (see, for example, NIOSH Method 9002 [NIOSH 1989] and OSHA method ID-191 [OSHA 1994]). This method also enables qualitative identification of asbestos types using morphology, color, and refiactive index. 

Examples of serious harm to workers from materials used and made in the manufacturing workplace are well known black lung disease and asbestosis stand out by the number of people affected and the severity of the results to long-term exposure to coal dust and asbestos fibers, respectively. Thus it is logical that, when dealing with bulk drugs (chemicals with potent and multiple biological activities), and as with thermochemi-... 

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